Exhaust purification system of internal combustion engine

An exhaust purification system of an internal combustion engine, comprising:

• an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine and having a catalytic function;
• a particulate filter arranged in the exhaust passage at a downstream side from the exhaust purification catalyst in a direction of flow of exhaust;
• an oxygen feed device feeding gas containing oxygen into exhaust gas flowing into the particulate filter at the downstream side from the exhaust purification catalyst in the direction of flow of exhaust;
• a detection device changing in output according to a concentration of ammonia in exhaust gas flowing out from the particulate filter;
• and
• a control device controlling the oxygen feed device and estimating an amount of deposition of particulate matter on the particulate filter,
• wherein the control device is configured to control the oxygen feed device so as to continuously or intermittently feed oxygen from the oxygen feed device to the particulate filter if a temperature of the exhaust purification catalyst is in a predetermined temperature range of equal to or greater than an activation temperature and an air-fuel ratio of exhaust gas discharged from a body of the internal combustion engine is a rich air-fuel ratio richer than a stoichiometric air-fuel ratio, and estimate the amount of deposition of particulate matter on the particulate filter based on the output of the detection device when feeding oxygen.